1. Field of Invention
This invention relates to a connection substrate, a method of manufacturing a connection substrate, a semiconductor device, and a method of manufacturing a semiconductor device, and particularly, a connection substrate and a method of manufacturing a connection substrate using an insulation material that is flexible, and a semiconductor device and a method of manufacturing a semiconductor device.
2. Description of Related Art
Conventionally, a multiple-chip-package (hereafter referred to as xe2x80x9cMCPxe2x80x9d) is known in which a wiring pattern is formed on a surface of an insulating film that is flexible (many films made of polyimide are used), and a plurality of semiconductor chips are mounted on this wiring pattern.
In the MCP having this structure, by folding an insulating film (in order to avoid a semiconductor chip) and folding the MCP itself, volume of the MCP can be reduced. Mounting of a semiconductor chip on another substrate can be accomplished by using a connection electrode formed in a rear side of a mounting surface of a semiconductor chip in the insulating film.
Furthermore, the above-mentioned connection substrate is attached to a copper foil, which becomes a wiring pattern on a surface of a flexible insulating film, and a wiring pattern is formed by coating a resist on this copper foil surface, performing exposure, and etching.
However, in the above-mentioned connection substrate, or a semiconductor device using the connection substrate, the following problems arise.
First, an insulating film has flexibility, so a connection substrate is easily deformed by an exterior force, or a force created by its own weight. Because of this, it is difficult to make an insulating film flat when exposure is performed. It is also difficult to make a wiring pattern narrow. Moreover, from the viewpoint of focusing, it is difficult to make wiring patterns and a pitch between wiring patterns narrow.
In addition, when wires between semiconductor chips or the like become complex, a method is known in which many wiring patterns are laminated. However, there is a problem that it is difficult to form many layers of wiring patterns because a wiring pattern is formed on a surface of an insulating film.
Furthermore, an insulating film has a thickness of approximately 50 xcexcm, and has a significant amount of force to fold the insulating film. Because of this, if the folding force is not sufficient, there is a possibility that folding of an insulating film will open due to a recovery force (returning to the state before folding).
Additionally, in a semiconductor device, when a semiconductor chip is mounted on a connection substrate, a wiring pattern, which is wound around a connection substrate, and a semiconductor chip are thermally compression-bonded by using a heating tool. However, a semiconductor chip formed of a mono-crystalline silicon and a connection substrate formed of a polyimide material are significantly different with respect to thermal expansion coefficients. Because of this, there is a problem that it is difficult to make a pattern pitch narrow.
Additionally, in a semiconductor device, even after a semiconductor chip is mounted, a connection substrate itself has flexibility. Therefore, if an exterior force is applied, it is easily deformed. Because of this, there is a possibility that, if an exterior force is applied during shipping or the like, a stress would be applied between a semiconductor chip and a connection substrate, and damage such as wire disconnection might may generated.
This invention addresses the above-mentioned problems with the conventional device. An object of this invention is to provide a connection substrate, a method of manufacturing a connection substrate, a semiconductor device and a method of a semiconductor device, which makes a width and a pitch of a wiring narrow, enables multi-layer wiring, and minimizes an effect of radiation heat of a heating tool or the like in the mounting of a semiconductor chip, so that damage, such as a wire disconnection or the like, is not generated by an exterior force.
In a method of manufacturing a connection substrate in accordance with an aspect of the invention, a metal wire is formed on a base, then an insulating material is applied to the metal wire to form a flexible insulating layer, another metal wire is formed on the surface of said insulating layer, thereby connecting the metal wires which sandwich the insulating layer, through a contact hole formed in the insulating layer. The metal wires and the insulating layer are then separated from the base. According to the connection substrate, the base has no flexibility. Thus, even if an exterior force or its own weight is applied, the surface is not deformed. Because of this, during interim processes wherein metal wires are formed, such as in an exposure process, a base does not move in a depth of field direction. Therefore, exposure with a narrow width can be performed, so metal wires with a narrow pitch and a narrow width can be formed.
Additionally, an insulating agent is applied to a base so as to cover a metal wire. Thus, the thickness of an insulating layer can be set to a dimension in which a metal wire can be embedded. Because of this, the thickness of the insulating layer can be made thin, and a force can be reduced when a connection substrate is folded. Furthermore, a recovery force (spring back) of an insulating layer itself becomes small, so opening of a folded connection substrate can be prevented (returning to a state before folding can be prevented).
In addition, in the method of manufacturing a connection substrate in accordance with another aspect of the invention, the plurality of metal wires and the plurality of insulating layers are laminated. According to the method of manufacturing the connection substrate, the metal wires can be connected vertically through contact holes formed in the insulating layer. Because of this, even if the number of wires increases, interference between the metal wires can be prevented, and winding of the metal wires in the connection substrate can be easily accomplished.
In the method of manufacturing a connection substrate in accordance with another aspect of the invention, the step of applying an insulating material onto the metal wire, and the step of forming another metal wire, thereby connecting the metal wires are repeated at least two times.
In the method of manufacturing a connection substrate in accordance with another aspect of the invention, the base is formed of glass. According to the method of manufacturing the connection substrate, light can be irradiated to the connection substrate from the rear side of the glass base (opposite side in which the connection substrate is manufactured). Because of this, if solvent or the like, having a separating reaction due to light irradiation is coated between a glass base and a connection substrate, after the connection substrate is formed, the glass base and the connection base can be easily separated by radiation light from the rear side of the glass base.
In the connection substrate in accordance with another aspect of the invention, the connection substrate is manufactured by the method of manufacturing the connection substrate as set forth above. Thus, metal wires with a narrow width and a narrow pitch can be formed.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, a connection substrate is formed on a base, wherein a metal wire is formed on a base, an insulating agent is applied to said metal wire to form a flexible insulating layer, another metal wire is formed on the surface of the insulating layer, a connection substrate is formed on the base, thereby connecting the metal wires which sandwich the insulating layer through a contact hole formed in the insulating layer. A semiconductor chip is then mounted on the metal wire which is bared, and the connection substrate is separated from the base. According to the method of manufacturing the semiconductor device, the base has no flexibility, so even if an exterior force or its own weight is applied, the surface is not deformed. Because of this, during interim processes wherein metal wires are formed, such as in an exposure process, a base does not move in a depth of field direction. Therefore, exposure with a narrow width can be performed, so metal wires with a narrow pitch and a narrow width can be formed.
Additionally, an insulating agent is applied to a base so as to cover a metal wire. Thus, the thickness of an insulating layer can be set to a dimension in which a metal wire can be embedded. Because of this, the thickness of the insulating layer can be made thin, and a force can be reduced when a connection substrate is folded. Furthermore, a recovery force (spring back) of an insulating layer itself becomes small, so opening of a folded connection substrate can be prevented (returning to a state before it is folded can be prevented).
In addition to the above-mentioned operation, in the case of mounting a semiconductor chip to a connection substrate, the connection substrate is formed on a flat base without flexibility, so a terminal of a semiconductor chip is not lifted up. Because of this, generation of conductive defects between a terminal of a semiconductor chip and a metal wire can be prevented. Furthermore, if a material which has a heat expansion coefficient which is close to the heat expansion coefficient of a semiconductor chip, is used for a base, in the case of mounting a semiconductor chip, by receiving radiation heat from a heating jig, an expansion difference between a metal wire side and a semiconductor chip side becomes large, and generation of a short circuit between adjacent terminals can be prevented.
Additionally, at a final stage after a semiconductor chip is mounted, a semiconductor device is separated from a base. Therefore, during interim processes such as conveying, a base supports a semiconductor device, and deformation of the semiconductor device due to an exterior force can be prevented.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, in the step of forming a connection substrate, the step of applying an insulating material onto the metal wire and the step of forming another metal wire, thereby connecting the metal wires are repeated at least two times.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, a connection substrate is formed on a base, wherein a metal wire to be connected to an electrode formed on a semiconductor chip is formed on a first base, an insulating material is applied onto the metal wire to form an insulating layer, another metal wire is formed on the insulating layer, thereby connecting the metal wires which sandwich the insulating layer, through a contact hole formed in the insulating layer. A second base is disposed on the connection substrate. The first base is separated from the connection substrate. A semiconductor chip is mounted on the metal wire that is bared. The connection substrate is separated from the second base. According to the connection substrate, the first base has no flexibility. Thus, even if an exterior force or its own weight is applied, the surface is not deformed. Because of this, during interim processes which metal wires are formed, such as in an exposure process, a base does not move in a depth of field direction. Therefore, exposure with a narrow width can be performed, so metal wires having a narrow pitch and a narrow width can be formed.
Additionally, an insulating agent coats a base so as to cover a metal wire. Thus, so the thickness of an insulating layer can be set to a dimension in which a metal wire can be embedded. Because of this, the thickness of the insulating layer can be made thin, and a force can be reduced when a connection substrate is folded. Furthermore, a recovery force (spring back) of an insulating layer itself becomes small, so opening of a folded connection substrate can be prevented (returning to a state before it is folded can be prevented).
Furthermore, after forming a connection substrate on a first base, a connection substrate is transferred to a second base. However, when a connection substrate is transferred to the second base, a surface which is separated from the first base of the connection substrate is exposed. A metal wire is formed on an exposure surface which is separated from the first base so as to form a butt joint with an element formed in a semiconductor chip. Therefore, even if a metal wire is not arranged in a semiconductor chip side, electrical conduction can be achieved between the semiconductor chip and the connection substrate.
In addition, in the case of mounting a semiconductor chip on a connection substrate, the connection substrate is formed on a flat base without flexibility, so a terminal of a semiconductor chip is not lifted up. Because of this, generation of conductive defects between a terminal of a semiconductor chip and a metal wire can be prevented. Furthermore, if a material which has a heat expansion coefficient that is similar to the heat expansion coefficient of a semiconductor chip, is used for a second base, in the case of mounting a semiconductor chip, by receiving radiation heat from a heating jig, an expansion difference between a metal wire side and a semiconductor chip side becomes large, and generation of a short circuit between adjacent terminals can be prevented.
Furthermore, in the final step after a semiconductor chip is mounted, a semiconductor device is separated from the second base. Therefore, the first base supports the connection substrate, and the second base supports the semiconductor device during interim processes such as conveying. Deformation of the semiconductor device due to an exterior force can be prevented.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, multiple semiconductor chip units are mounted on the connection substrate. According to the method of manufacturing the semiconductor device, by mounting a plurality of semiconductor chips on the connection substrate, connection can be established between the semiconductor chips. Thus, multi-functions can be accomplished. In addition, the insulating layer has flexibility, so the connection substrate can be folded between the semiconductor chips, and volume of the semiconductor device can be reduced.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, the plurality of metal wires and the plurality of insulating layers are laminated. According to the method of manufacturing the semiconductor device, connection can be accomplished between the upper and lower metal wires via contact holes formed in the insulating layer. Because of this, even if the number of wires increases, interference of the metal wires can be prevented, and winding of the metal wires in the connection substrate can be easily accomplished.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, the base is formed of glass. According to the method of manufacturing the semiconductor device, light can be irradiated to the connection substrate from the rear surface side (the opposite side in which the connection substrate is manufactured) of the glass base. Because of this, if solvent or the like, having a separating reaction due to light irradiation is coated between a glass base and a connection substrate, after the connection substrate is formed, the glass base and the connection base can be easily separated by irradiation light from the rear side of the glass base.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, the base is formed of silicon. According to the method of manufacturing the semiconductor device, when the semiconductor chip is mounted on a connection substrate, the connection substrate closely attaches to a base formed of silicone. Therefore, the base has a thermal expansion coefficient that is substantially the same as the thermal expansion coefficient of the semiconductor chip. Even if radiation heat is received from a heating jig which is used for mounting of the semiconductor chip, an expansion difference becomes large between a metal wiring side and a semiconductor chip side, and short-circuiting or the like between adjacent terminals can be prevented.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, the second base is formed of glass. According to the manufacturing the semiconductor device, light can be irradiated to the connection substrate from the rear surface side (the opposite side in which the connection substrate is manufactured) of the glass base. Because of this, if solvent or the like, having a separating reaction due to light irradiation is coated between a glass base and a connection substrate, after the connection substrate is formed, the glass base and the connection base can be easily separated by irradiation light from the rear side of the glass base.
In the method of manufacturing a semiconductor device in accordance with another aspect of the invention, the second base is formed of silicon. According to the method of manufacturing the semiconductor device in accordance with another aspect of the invention, when the semiconductor chip is mounted in a connection substrate, the connection substrate closely attaches to a second base formed of silicon. Therefore, the base of a thermal expansion coefficient is substantially the same as the semiconductor chip of a thermal expansion coefficient. Even if radiation heat is received from a heating jig which is used for mounting of the semiconductor chip, an expansion difference becomes large between a metal wiring side and a semiconductor chip side, and short-circuiting or the like between adjacent terminals can be prevented.
The semiconductor device in accordance with another aspect of the invention is manufactured by the method of manufacturing a semiconductor device as set forth in any of the above aspects of the invention. According to the semiconductor device, the insulating layer has flexibility, and a thin film can be achieved, so that the connection substrate can be easily folded. Furthermore, a recovery force (spring back) of an insulating layer itself becomes small, so opening of a folded connection substrate can be prevented (returning to a state before folding can be prevented).